Automatic switch



Feb. l0, 1942. c. HfwoLF ErAl 2,272,784

AUTOMATIC SWITCH .Filed May 13, 1940 4 sheets-sheet 1 sia 'VW/ MilATTORNEYS 1 N VEN TORS AUTOMATIC SWITCH Filed May 15, 1940 4sheets-sheet 2 ATTORNEYS Feb. 1o; 1942.

AUTOMATIC SWITCH Filed May l5, 194C 4 sheets-sheet s Miam! Feb. 10,1942.c. H. woLF Erm. 2,272,784

AUTOMATIC SWITCH Filed, May l5, 1940 4 Sheets-Sheet 4 1N VENTORS,

Wan/e5 d. /fI/o/f Foy f.' en/waff E ATTORNEYS Patente-d Feb. 10, 1942UNITED lSTATES PATENT OFFICE AUTOMATIC SWITCH Charles H Wolf and Roy E.Gearhart, Kansas City, Mo.; said Gearhart assigner to said WolfApplication May 13, 1940, Serial No. 334,712

19 Claims.

This invention relates to electric circuit breakers of the automatictype wherein manually setable means is incorporated for determining theperiod of time throughout which the circuit controlled by the switchremains closed.

One of the primary objects of this invention is to provide simple,inexpensive, compact and eicient circuit making and breaking structure,the character of which permits its use wherever electric appliances orlights are to be controlled, and especially where it is undesirable toburden the installation with heavy, complicated and expensive apparatus.

This invention has for one of its aims the provision of an automaticswitch wherein is incorporated thermally responsive structure, theheating and cooling of a part of which serves to advance certain partsof the switch through a stepby-step movement and toward a position whereadvancement from one step to another will serve to operate the blade ofthe switch to the opencircuit position,

Another important object of this invention is the provision of anautomatic electric switch, the parts of which are manually settable sothat the switch blade may remain in the closed-circuit position for a'predetermined length of time without the employment of expensive,complicated and intricate mechanism.

Another object of the invention is to provide an automatic switch of theaforementioned character having thermally responsive structure thereinand having as a part thereof, at least one reciprocating element whichis carried through its path of travel by the successive heating andcooling of a heating element, the supply of energy thereto beingintermittently and periodically interrupted as the said reciprocatingelement is moved.

A still further aim of this invention is the provision of an electricswitch, which has as a part thereof, a manually movable trigger operablyconnected to the switch blade in such manner as to cause the switchblade to assume the closedcircuit position upon movement of the triggerfrom one end of its path of travel to the other end thereof, and tothereafter cause the switch blade to assume an open-circuit positionwhen the trigger is moved along the same path of travel as thattraversed during the next preceding operation, which resulted indisposing the switch blade in the closed-circuit condition.

A still further object of this invention is to provide in an electricswitch, a manually operable trigger yieldably maintained at one end of apath of travel in a normal position and equipped with parts that willfirst move the switch blade to the closed-circuit position andimmediately thereafter upon movement of the trigger, again will move theswitch blade to the closed-circuit position.

A further and additional salient object of this invention is theprovision of an automatic eleotric time switch, the parts of which maybe housed in a compact case interposed in the conventional extensionleading to 9, sign, light or electric appliance of any character, thecurrent to which is to be interrupted after a predetermined length oftime, which may be governed by a settable dial supported on the case.

Other objects of the invention include the manner of constructing, themeans for embodying the concepts thereof, and therefore, additional aimswill appear during the course of the following specification, referringto the accompanying drawings wherein:

Figure 1 is a side elevational view of an automatic switch made inaccordance with the present invention.

Fig. 2 is an enlarged side elevational view of the automatic switch withone-half of the casing removed to reveal the operating parts.

Fig. 3 is a similar view but with the switch blade in the closed-circuitposition.

Fig. 4 is a fragmentary side elevational View of a portion of the switchwith the parts thereof in an intermediate position.

Fig. 5 is a similar view showing the parts of the switch in the' placeassumed thereby the instant before the switch blade returns to theopencircuit position.

Fig. 6 is a longitudinal irregular sectional View through an automaticswitch, taken on line VI-.VI of Fig. 3. v

Fig. 'l is a fragmentary side elevational view of the switch partsshowing the shunt circuit switch in the open position.

Fig. 8 is a transverse cross sectional View taken on line VIII-VIIIofFig. 2.

Fig. 9 is a similar cross sectional View taken on line IX-IX of Fig. 3i.

Fig. 10 is an enlarged fragmentary sectional view taken on line X-X ofFig. 4.

Fig. 1l is a detailed sectional View taken on line XI-XI of Fig. 10.

Fig. 12 is a stretch-out perspective view of the manually movable dialknob and some of the parts associated therewith.

Fig. 1.3 is a wiring diagram employed in the switch.

Fig. 14 is another wiring diagram including a signal lamp.

Fig. 15 is a face view of an automatic switch made to embody a modifiedform or the invention.

Fig. 16 is a fragmentary plan view of the switch shown in Fig. 15.

Fig. 17 is a wiring diagram illustrating the manner of connecting theelectrical resistor' of the switch in series.

Fig. 18 is another wiring diagram indicating the manner in which anautomatic switch embodying the invention, may be used in buildings; and

Fig. 19 is a fragmentary view of a portion of the switch illustratingthe manner in which it may be constructed so that the switch blade is inthe closed-circuit position with the circuit supplying energy to theresistor, open.

Because of the large number of advantages arising from a compact,automatic switch that may be placed in an extension cord 20 ofconventional type, the same is conned in a case 22 formed of two matingsections held together by tie-bolts 24. The ends of case 22 are providedwith bores 25 through which extension 20 may pass to permit theconductors 28 and 30 thereof to be attached to connection 32 of resistor34 and switch point 36 respectively.

When interposing the switch in an ordinary extension cord 2D, conductors28 and 30 are severed and while two of the ends so produced are attachedto connection 32 and switch point 36 as above mentioned, the other twoends are secured to connection 32 and switch point 38. Switch points 36and 38 are interconnected by switch blade 40 when the latter is in theclosedcircuit position.

A yoke 42 carries blade 40 so that the latter is moved with a snapaction. Such action is obtained through the medium of the conventionalpast-center spring 44, one end of which bears against the bight ofU-shaped yoke 42, whiile the other end thereof rests against the innerface of trigger 46. The trigger is pivotally mounted on pin 48 and areturn spring 50 yieldably maintains the trigger in th-e normalposition, shown in Figs. 2 and 3.

A stationary stop plate 52, rigid with case 22, has shoulders 54 and 56thereon to limit the movement of yoke 42.

An auxiliary yoke 58 is mounted upon pin 48 intermediate its ends. Oneend of auxiliary yoke 56 carries a laterally extending stub 60, whilethe other end of auxiliary yoke 5B is yieldably held in spaced relationto the inner face of trigger 46 by spring 62.

A flag 64 integral with yoke 42 bears the usual indicia, i. e. Off andOn, which appears before Window 65 to reveal to the user the position ofswitch blade 40.

An arm 66 pivotally mounted near one end as at 68 to case 22, extendslongitudinally to a point.

adjacent to yoke 42 where spring 70 yieldably maintains the free endthereof against stop 12. A shoulder 14 and a cam face 16 cooperates withyoke 42 so that as the yoke is raised to the position shown in Fig. 3,the bight thereof will snap above shoulder `|4to be retained thereby.

vA laterally projecting finger 18 lies directly behind ratchet 80through which is passed a transverse pintle 82. Theinner end of pintle82 moves against a portion of finger 18 to release yoke 42 in a mannermore fully hereinafter set down.

A stop 84 on arm 'intermediate the ends thereof cooperates withspecially formed release member 86. This release member'is shiftablymounted upon arm 66 through the medium of screw 88 that passes throughslot 90. An extension 92 integral with release member 86 embraces arm 66and passes therearound to a point where it is engaged by compressionspring 94, one end of which is rigid with case 22 as at 96. A downturnedportion 98 of release member 8B bears against one longitudinal edge ofarm 86 to limit the swinging movement of member 86 about the axis ofscrew 88.

Release member 86 is laterally offset, as shown in Figs. 2 and 3, forexample, so that a notch |00 thereof lies adjacent to stub 60. The upperfree end of release member 86 underlies yoke 42 and limits the downwardmovement of this yoke when the same is in the position shown in Fig. 2,for example.

Ratchet 80 is provided with ratchet teeth in the annular peripherythereof and is mounted for rotation upon post |02 anchored to case 22. Aspring |04 has one end fastened to ratchet,

. while the other end is secured to the post for the purpose ofyieldably maintaining ratchet 80 in a set position.

Pintle 82 extends laterally to each side of ratchet 80 and is in thepath of travel of setting disc |06 which has laterally extending pin|08. This setting disc is rotatably mounted in bracket ||0 carried by aportion of cas-e 22, as shown in Fig. 6, and shaft I I2 on sett-ing disccarries a knob I|4 having indicia ||6 on the outer face thereof. Thisknob I I4 is mounted in an opening I|8 provided in the side wall of case22 and projects above the outer plane of case 22 so that the operatormay easily manipulate the parts associated therewith, for the purpose ofsetting any one ofthe numerals forming indicia IIB opposite to marker|20 when the switch is set to allow the switch bladeV 40 to remain inthe closedcircuit position a predetermined length of time.

The thermally responsive structure includes re- Y sistor |22 whichcircumscribes the bi-metallic strip |24, one end of which is anchored asat |28, while the free end thereof enters bifurcated head |28 formed onthe lower end of rocker element |30. Rocker element |30 is pivotallymounted on shaft |32 as is bell-crank lever |34. One arm of lever I 34carries a head |36 of conducting material which serves to join switchpoints I 38 and |40 when the thermally responsive structure is in thepositions shown in Figs. 2 to 5.

The other arm of bell-crank lever |34 carries dog |42, the tooth |44thereof being engageable with the teeth of ratchet 80. Dog |42 has apart projecting longitudinally beyond tooth |44 for engagement beneathyoke 42 and spring |46 yieldably urges dog |42 toward ratchet 80. A pin|48 pivotally attaches one end of dog |42 to bellcrank lever |34. Theextreme upper end of one leg of bell-crank lever |34 is provided withspaced apart ears |50 and |52 respectively, between which rides pin |54on rocker element |30. A spring |56 anchored to case 22 as at |58 andattached to the free end of rocker element |30. assists strip |24 inmoving element |30.

Pawl pivotally mounted upon case 22 as at |62 is yieldably maintainedagainst ratchet 80 by spring |64. This pawl has an extension which liesbehind the extended portion of dog |42 and the free ends of dog |42 andpawl |60 are-engageable by yoke 42 when the latter is at one end of itspath of travel.

A conductor wire |66 joins switch point 38 and switch point |38, andanother wire |68 joins switch point |40 and resistor |22.

The circuit employed in the switch just described, is shown in Fig. 13.It is assumed that the switch is controlling the ilow of current to lamp|10. If the switch blade 40 is closed, as illustrated in Fig. 3, currentwill pass to lamp through wires 28 and 28 and thence back to the sourcethrough wires 30 and 30' and switch blade 40. Resistor |22 is in shuntand current will pass through resistor |22 by way of connection 32, wire|68, closed contacts |40, |36, |38 and wire |66.

Assuming that the switch parts are in the,

ywhenever one of the numerals on knob ||4 arrives opposite to marker|20.A

When the numeral four is disposed opposite to marker |20, the inner endof pin 82 in ratchet 80 will be spaced from the inturned portion oflinger 18 a distance which will require the thermally responsivestructure four hours to move pin 82 against nger 18. Thereafter thecircuit is closed by an upward movement on trigger 46 which snaps yoke42 from the position illustrated in Fig. 2 to the position shown in Fig.3. The window 64 will reveal that the switch is on" and yoke 42 will beresting upon shoulder 14 of arm 66. Switch blade 40 will bridge switchpoints 36 land 38 and current will ow through extension 20 and likewisethrough the shunt circuit wherein is disposed resistor |22.

If the switch is left in the,condition shown in Fig. 3, the thermallyresponsive structure will proceed to move ratchet 80 in a step-by-stepfashion against the force of spring |04. As the temperature of resistor|22 is raised strip |24 will bend to move bell-crank lever |34 androcker clement about the axis of shaft |32. Spring |56 will assist thequick movement of the free end of rocker element |30 from the positionshown in Fig. 2 to that position shown in Fig. 7.

When the thermally responsive parts have moved through one step asavresult of a temperature rise, connector |36 will open switch points|38 and |40 and the resistor together with strip |24 will cool. Whenstrip |24`has cooled and returned to its normal straight position,rocker element |30 will again assume the position'it had in thebeginning to cause switch points |38 and |40 to be closed. Heating againtakes place and the operation just describedV is repeated.

As strip |24 cools to move dog |42 back to the point of beginning shownin Fig. 3, pawl |60 will hold ratchet wheel 80 against returningto itsnormal position under the inuence of spring |04. Thus, the step-by-stepmovement, which is imparted to ratchet 80, will gradually move pin 82against nger 18. When such relation is established, arm 66 will be movedto the left (Fig. 3) and yoke 42 will move down under the influence ofcompression spring 44 against the outer free extended ends of dog |42and pawl |60. Spring 44 has the axis thereof yat an angle to the axis ofyoke 42 for the purpose of creating a conventional past center action.lThese two elements will be separated from operative engagement withratchet 80 and yoke 42 will again rest on the upper end of releasemember 86. When yoke 42 does move because of its being released by arm66, switch blade 48. will be snapped to the open-circuit position.

Assuming that the switchA has been set as above set down and it isdesired to manually open the circuit by a second manipulation of trigger46, the parts are in the relation illustrated in Fig. 3. Another upwardmovement on l trigger 46 against the force of return spring 50 willcause auxiliary yoke 58 to move release member 86 to the position shownin Fig. 4, because stub 60 will engage notch |00 as trigger 46 forcesauxiliary yoke 58 in a counter-clockwise direction about'the axis of pin48. Such interengagement of parts 60 and |00 will allow spring 94 toforce release member 86 upwardly after it has been carried away frombelow stop 84. With upward pressure exerted on trigger 46, the partswill be as shown in Fig. 4. As soon as theupward pressure on trigger 46is released, the side of release member 86 will move against stop 84, asshown in Fig. 5. Such action will carry arm 66 to the left (Figs. 3 to5), against the action of spring 10 and yoke 42 will be al lowed toreturn to the position shown in Fig. 2. When this movement takes place,yoke 42 will strike the upper end of release member 86, spring 94 willbe compressed, and release member 86 will assume the normal positionillustrated in Fig. 2.

From the foregoing it will be apparent that with the thermallyresponsive structure, set for the maximum .time (approximately eighthours, as indicated in the drawings), the switch may be employed asmeans for manually making and breaking the circuitthroughout the day andyet at any time, be quickly and easily converted into a time switchwhich will break the circuit, as predetermined by the user.

The Wiring diagram of Fig. 14 is precisely the same as that of Fig. 13,except a signal lamp |16 isprovided to indicate that the switch is inthe off position. When switch blade 40 is off it bridges points |18 and|80 so that current is supplied from wire 28 through Wire |82, wire |84,wire |86, wire |88 and wire 30 to signal lamp |16. A switch |90 isemployed to selectively render the ,signal circuit operative.

The circuit in Fig. 17 illustrates the manner `in which resistor |22 maybe connected in series and not in shunt. The signal lamp |16 is employedto indicate that the switch Ais 01T and lamp |10 is the electricaldevice to which current is being supplied. When switch blade 40 isbridging points 38 and 36, the series circuit may be traded as follows:Wire 28, wire |92, resistor |22, wire |94, switch points |40, |36 and|38, wire 28', wire 30', switch points 38 and 36, which are closed byblade 40 and thence through lwire 30. Obviously, the circuit for signallamp |16 is as follows: Wire 28, wire |96, lamp |16, switch |98, wire200, switch points 200 and` 204, and wire 206.

An example of the manner in 'which this time switch may be employed 'iisdiagrammatically shown in Fig. 18. The switch blades 40 located in theswitches in several rooms of a hotel, for example, control the ow ofcurrent from main wire 208 back to main wire 2|0. Lamps |10 arecontrolled without the influence of the thermally responsive structurewhich would automatically open the circuit after a predetermined periodof time.

In practice, for example, the thermally responsive structure is set forone hour and when the main switch 2|2 is closed by the proprietor, allof the lights will be controlled by the thermally responsive structureassociated with each lamp |10. It is merely necessary to run anadditional line 2|4 to the rooms where the switches are located so thatthe resistors |22 may form a part of the circuit control lamps |10.

The switch illustrated in Figs. and 16 embodies a modied form of theinvention. The parts throughout are precisely the same with theexception of the manually operable means employed to set the thermallyresponsive structure.

In this instance, a lock 300 .with a key 302 is used to turn shaft 304,which serves to move the setting disc |06. This setting disc is rigidwith shaft 304, as is bevelled gear 306 and a gear 308 on shaft 3| 0transmits the necessary rotary movement to setting disc |06 toaccomplish the .end hereinabove described.

'I'he switch in Figs. 15 and 16 is housed in an ordinary switch boxhaving a face plate 3|2 upon which indicia 3|4 is arranged. An opening3|6 receives lock 300 and the use of key 302 prevents unauthorizedpersons from setting the switch or changing the period of time thecircuit remains closed.

The manner of altering the structure of the switch so that no currentflows to resistor |22 when switch blade 40 is in the closed-circuitposition, is shown in Fig. 19. In this modification'return spring 50 isnot employed and trigger 46 will remain at either end of its path oftravel under the iniluence of spring 44. Auxiliary yoke 58 has a branch3|0 thereon which carries contact point 320 that cooperates with contactpoint 322 on switch point 38. A ilexible conductor 324 joins switchpoint 320 and point |38.

After the switch parts are moved to the position shown in Fig. 19, yoke42 will be held in the closed-circuit position by shoulder 14 on arm 66.Thereafter, if the thermally responsive structure is to be renderedoperative, trigger 46 is manually moved down or back to its normalposition or the point of beginning. Such action will leave yoke 42 inthe position shown where switch blade 40 remains in the closed-circuitposition. Points 320 and 322 will be moved together to complete thecircuit to resistor |22.

An automatic switch made in accordance with the concepts of thisinvention is susceptible to a large number of uses and while someindication -of the commercial embodiment has been made evident duringthe course of the foregoing specication, it is understood that formsother than those illustrated and described may be made without departingfrom the spirit of the appended claims.

Having thus described the inventionkuwhat is claimed as new and desiredto be secured by Letters Patent is:

1. In an electric switch of the character described, a switch blademovable to the closed and open-circuit positions; a trigger movable bymanual manipulation along a path of travel to and from a normalposition; means operable by two successive movements of the trigger fromthe normal position to cause the switch blade to assume theclosed-circuit and the open-circuit positions respectively; and meansfor yieldably maintaining the trigger in the normal position.

2. In an electric switch of the character described, a switch blademovable to the closed and open-circuit positions; a trigger movable bymanual manipulation along a path of travel to and from a normalposition; means operable by two successive movements of the trigger fromthe normal position to cause the switch blade -to change its positionwith respect to the closed and open-circuit positions with a snapaction; and means for yieldably maintaining the trigger in the normalposition.

3. In an electric switch of the character described, a switch blademovable to the closed and open-circuit positions; a yoke supporting theswitch blade; a trigger movable along a path of travel to and from anormal position; means for yieldably maintaining the trigger in thenormal position; a spring between the trigger and said yoke for movingthe yoke and said switch blade with a snap action; a catch to hold saidswitch blade in the closed-circuit' position; and parts operable bymovement of the trigger from the normal position to release the switchblade.

4. In an electric switch of the character described, a switch blademovable to the closed and open-circuit positions; a yoke supporting theswitch blade; a trigger movable along a path of travel to and from anormal position; means for yieldably maintaining the-trigger in thenormal position; a spring between the trigger and said yoke for movingthe yoke and said switch blade to the closed-circuit position with asnap action upon movement of the trigger from the normal position; acatch to hold said switch blade in said closed-circuit position as thetrigger is returned to the normal position by means for maintaining thesame in that position; and parts operable by the next successivemovement of the trigger from the normal position to release the switchblade.

5. In an electric switch of the character described, a switch blademovable to the closed and open-circuit positions; a yoke supporting theswitch blade; a trigger movable along a path of travel to and from anormal position; means for yieldably maintaining the trigger in thenormal position; a spring between the trigger and said yoke for movingthe yoke and said switch blade to the closed-circuit position with asnap action upon movement of the trigger from the normal position; acatch to hold said switch blade in said closed-circuit position as thetrigger is returned to the normal position by the means for maintainingthe same in that position; and parts operable by the next successiveVmovement of the `trigger from the normal position to release the switchblade, said parts being held in an inoperative position by the said yokewhen the switch blade is in the open-circuit position.

6. In an electric switch of the character described,`a switch blademovable to the closed and open-circuit positions; a yoke supporting theswitch blade; a trigger movable along a path of travel to and from anormal position; means for yieldably maintaining the trigger in thenormal position; 4a spring between the trigger and said yoke for movingthe yoke and said switch blade to the closed-circuit position with asnap action upon movement of the trigger from the normal position; acatch to hold said switch blade in said closed-circuit position as thetrigger is returned to the normal position by the means for maintainingthe same in that position; and parts operable by the next successivevmovement of the trigger from the normal position to release the switchblade, said parts being shiftable to the operative position uponmovement of the switch blade to the closed-circuit position.

7. In an electric switch of the character described, a switch blademovable to the closed and open-circuit positions; a yoke supporting theswitch blade; a trigger movable along a path of travel to and from anormal position; means for yieldably maintaining the trigger in thenormal position; a spring between the trigger and said yoke for movingthe yoke and said switch blade to the closed-circuit position with asnap action upon movement of the trigger from the normal position; acatch to hold said switch blade in said closed-circuit position as thetrigger is returned to the normal position by the means for maintainingthe same in that position; an auxiliary yoke adjacent to the trigger foroperation thereby; a release member shiftable by the auxiliary yoke forreleasing the catch to cause the switch blade to move to the opencircuitposition; and structure for holding the release member inoperative untilthe trigger is moved from the normal position after once being movedfrom said position to shift the switch blade to `the closed-circuitposition.

8. In an electric switch of the character described, a switch blademovable to the closed and open-circuit positions; a yoke supporting theswitch blade; a trigger movable along a path of travel to and from anormal position; means for yieldably maintaining the trigger in thenormal position; a spring between the trigger and said yoke for movingthe yoke and said switch blade to the closed-circuit position with asnap action upon movement of the trigger from the normal position; acatch to hold said switch blade in said closed-circuit position as thetrigger is returned to the normal position by the means for maintainingthe same in that position; an auxiliary yoke adjacent to the trigger foroperation thereby; a release member shiftable by the auxiliary yoke forreleasing the catch to cause the switch blade to move to theopen-circuit position; and structure for holding the release memberinoperative until the trigger is moved from the normal position afteronce being moved from said position to ,shift the switch blade to theclosed-circuit position, said release member being held in a positionwhere it is inoperative by the auxiliary yoke by the first mentionedyoke when the switch blade is in the open-circuit position.

9. In an electric switch of the character described` a switch blademovable to closed and open-circuit positions with a snap action; atrigger; means operable by the trigger to cause the switch blade toassume the closed-circuit position;l a catch to hold the switch bladeinthe closed-circuit position; a member movable step-by-step for releasingthe catch to cause the switch blade to assume the open-circuit position;and thermally responsive structure for'imparting step-by-step movementto the said member. 4

10. In an electric switch of the character described, a switch blademovable to closed and open-circuit positions with a snap action; a

closed-circuit position;

closed-circuit position; a member movable stepby-step for releasing thecatch to cause the switch blade to assume the open-circuit vposition;and thermally responsive structure for imparting step-by-step movementto the said member, said member being formed to release the catch whenbeing moved through a certain one of its steps.

11. In an electric switch of the character described, a switch blademovable to the closed and open-circuit positions with a snap action; atrigger; means operable by the trigger to cause the switch blade toassume the closed-circuit position; a catch to hold the switch blade inthe closed-circuit position; a member movable stepby-step for releasingthe catch to cause the switch blade to assume the open-circuit position;and thermally responsive structure for imparting step-by-step movementto the said member. said thermally responsive structure having means forcontrolling the flow of a heating medium thereto operable to supply saidmedium during every other step of the step-by-step movement.

l2. In an electric switch of the character described, a switch blademovable to the closed and open-circuit positions with a snap action; atrigger; means operable by the trigger to cause the switch blade toassume the closed-circuit position; a catch to hold the switch blade inthe closed-circuit position; a member movable stepby-step for releasingthe catch to cause the switch blade to assume the open-circuit position;and thermally responsive rocking element operably engaging the lastmentioned member during movement in but one direction.

13. In an electric switch of the character described, a switch blademovable to the closed and open-circuit positions with a snap action; atrigger; means operable by the trigger to cause the switch blade toassume the closed-circuit position; a catch to hold the switch blade inthe a member movable through a successive number of stations forreleasing the catch when one of the stations is reached; thermallyresponsive structure for imparting step-by-step movement to the memberto move the same through the number of stations; and means for settingthe member where any one of a predetermined number of stations must bepassed before the catch is released.

14. In an electric switch of the character described, a switch blademovable to the closed and open-circuit positions with a snap action; atrigger: means operable by the trigger to cause the switch blade toassume the closed-circuit position; a catch to hold the switch blade inthe closed-circuit position; a movable member for releasing the catch tocause the switch blade to assume the open-circuit position when themember reaches a certain position; a reciprocating element for movingthe member as the element passes along but one of its paths of travel;and thermally responsive structure for carrying the reciprocatingelement along its path of travel in said one direction.

Y 15,'In an electric switch of the character described, a switch blademovable to the closed and open-circuit position with a snap action; atrigger; means operable by the trigger to cause the switch blade toassume the closed-circuit position; a catch to hold the switch blade inthc closed-circuit position; a movable member for releasing the catch tocause the switch blade to assume the open-circuit position when themember reaches a certain position; a reciprocating element for movingthe member as the element passes along but one of its paths of travel;and thermally responsive structure for carrying the reciprocatingelement along its path of travel in said one direction, said thermallyresponsive structure having an electrical heating element and a switchfor controlling the supply of current to said element.

16. In an electric switch of the character described, a switch blademovable to the closed and open-circuit positions with a snap action; atrigger; means operable by the trigger to cause the switch blade toassume the closed-circuit position; a catch to hold the switch blade inthe closed-circuit position; a movable member for releasing the catch tocause the switch blade to assume the open-circuit position when themember reaches a certain position; a reciprocating element for movingthe member as the element passes along but one of its paths of travel;and thermally responsive structure for carrying the reciprocatingelement along its path of travel in said one direction, said thermallyresponsive structure having an electrical heating element and a switchfor controlling the supply of current to said element, said switchhaving connection with 'the said reciprocating element and adapted toclose the circuit supplying current to the heating element as thereciprocating element is carriedL along its path of travel in said onedirection.

17. In an electric switch of the character described, a switch blademovable to the closed and open-circuit positions with a snap action; atrigger; means operable by the trigger to cause the switch blade toassume the closed-circuit position; a catch to hold the Switch blade inthe closed-circuit position; a movable member for releasing the catch tocause the switch blade to vassume the open-circuit position when themember reaches a certain position; a reciprocating element for movingthe member as the element passes along but one of its paths of travel;and thermally responsive structure for carrying the reciprocatingelement along its path of travel inthe said reciprocating element andadapted to close the circuit supplying current to the heating element asthe reciprocating element is carried along its path of travel in saidone direction, said switch being opened when the reciprocating elementreaches one end of its path of travel in said one direction to allow thethermally responsive structure to be returned to the other end of itspath of travel through the cooling of the thermally responsivestructure.

18. In an electric switch of the character described, a switch blademovable to the 'closed and open-circuit positions with a snap action; atrigger; means operable by the trigger to cause the switch blade toassume the closed-circuiti` position; a catch to hold the switch bladein the closed-circuit position; a member movable stepby-step forreleasing the catch to cause the switch blade to assume the open-circuitposition; thermally responsive structure, including a bendable strip,and electrical means for supplying heat thereto, for impartingstep-by-step movement to the said member; and a switch for controllingthe flow of current to said electrical heating means, said switch beingadapted to close during every other step of said movement and to openduring alternate intervening steps whereby heating and cooling of thethermally responsive structure occurs to move the releasing member.

19.In an electric switch of the character described, a switch blademovable to the closed and open-circuit positions with a snap action; atrigger; means operable by the trigger to cause the switch blade toassume the closed-circuit position; a catch to hold the switch blade inthe closed-circuit position; a ratchet wheel having a pin thereonengagable with the catch to release the same when the pin is in acertain position; a dog adapted to move the ratchet wheel in onedirection about its axis of rotation; thermally responsive structure forcarrying the dog through a path of travel to so move the ratchet; andmeans for supplying a heating mediumv to the said structureas the dog isadvanced to move the ratchet, the said thermally responsive structurebeing adapted to return the dog to the point of beginning by its actiond ue to cooling.

ROY E. GEARHART. CHARLES H. WOLF.

